Thanks for the reply, he didn't by any chance have an original xbox gamertag which was ported to the 360 right? I don't remember which board that came from, but someone said it would only work if the gamertag was the same as an original xbox live one.
Edit: Had to use the code on Xbox.com, my...
So am I correct in assuming that the old original Xbox Live cards still work in creating and extending Xbox 360 Live accounts? I know this was the case previously, but when I called Xbox Live they reported the contrary. I'm not sure the CSR knew what she was talking about though...